Air-supply to mechanical stokers.



W; R. WOOD.

MR SUPPLY T0 MECHANICAL STOKERS.

APPLICATION men MAY 13. 1915.

1,821,125. Patented Apr. 3,1917.

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. WOOD.

AIR SUPPLY T0 MECHANICAL STOKERS.

APPLICATION FILED MAY 13' 19 15.

Patented Apr. 3, 1917.

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AIR-SUPPLY T0 MECHANICAL STOKERS.

Specification of Letters Patent.

Patented Apr. 3, 1917.

Application filed May 13, 1915. Serial No. 27,872.

To all whom it may concern:

Be it known that I, VVILFRED RO'rI-IERY Wooo, a citizen of. the UnitedStates of America, and a resident of London, England, have invented acertain new and useful Improvement in Connection with the Air- Supply toMechanical Stokers, of which the following is a specification.

In mechanical stokers to which it is de sired to supply the air to theunderside of traveling grates and maintain a pressure above that of theatmospheric pressure, considerable difficulty is frequently encounteredin so arranging the air ducts which connect the stokers with the fan asto avoid a loss in the pressure set up by the fan, and also a loss ofair through leakage. There is also considerable expense involved in themanufacture and arrangement of such ducts and occasionally it is foundthere is insufiicient roomfor a really practical arrangement.

There are also certain complications as regards connecting up. the ductswith the stokers. This is particularly the case with traveling grate(chain grate) stokers (and it is to this class that the presentinvention relates) which are usually so mounted on wheels, or otherwise,as to be capable of removal and replacement.

Among other proposals heretofore made is one to place a fan withinthestoker itself, between the upper portion of the grate which carries thefuel in, and the lower or returning portion of the traveling grate. Thisproposal is almost impracticable owing to the dirt and dust causingserious wear 7 and trouble with the shaft driving the fan,

which it is necessary to run at a very high speed.

Further, in this posltion there is usually insufiicient room to place anefficient fan,

that is, a fan that would supply the necessary quantity of air withoutabsorbing too much power. In this position too, the wearing parts aremore orjless inaccessible.

It has further been proposed to employ a fan external to the furnacegrate and de livering the air to the ash pit the position of the damperof such fan being regulated by the steam pressure in the boiler as isalso the feed of fuel the arrangement being such that as the steampressure rises the feed of fuel and air is decreased and as the pressure falls both air and fuel are increased but such arrangement has notprovided the essential for practical working namely the power toinstantly alter the relative rates of fuel and air feed nor did itpropose that separate fans mounted 'on the same shaft should deliver theair upon opposite sides of the grate and finally the arrangement did notpermit of the removal of the grate and fans without breaking connectionsthese being important features of the present invention.

According to this invention it is proposed to overcome the severaldifliculties described by mounting the fans on the stoker, that is,self-contained therewith or supported thereby, but in a position withoutinstead of within the grate, and where high speeds are perfectlypracticable, and all the parts are accessible and the shaft and fans soplaced as to not present any inconvenience in the operation of thestoker, or aifect the accessibility to other parts of the stoker. At thesame time the fans are placed in such a position as to enable shortconnections or ducts of a permanent character to be employed forcarrying the air from the fans to the air chambers beneath the grate,and all these advantages may be gained by mounting the fans and primemover if desired on the stoker hopper, or removable front plate.

The fans may be driven from a source of power not self-contained withthe stoker, or they may be driven by a source of power such as anelectric motor or by a steam turbine selfcontained with the stoker. Ineither case the mechanism which drives the stoker itself may be soconnected up to the source of power that a variation in the speed of theprime mover gives a like variation to the speed of the grate. But aspeed regulating apparatus between the stoker driving gear and the fansor the source of power should be employed so that the relative speed ofgrate and fans may be readily adjusted from time to time.

In a convenient construction according to the invention two fans aremounted on opposite sides of the hopper, these two fans being connectedtogether by a shaft, also carrying an electric motor, or steam turbine,so as to secure a direct drive. Connected with the shaft is a wormreduction gear carrying at the bottom end of the worm wheel shaft asprocket wheel, said sprocket wheel through the agency of a chain beingcaused to drive the stoker either direct or through a speed regulatinggear.

From each fan a connection or duct is carried down the side of thehopper or front plate and into the side of the stoker, and in eachconnecting pipe an air gate is preferably arranged so that the supply ofair to each side of the stoker, that is the supply of air from the twofans, may be regulated.

To enable the invention to be fully understood it will now be describedby reference to the accompanying drawings, in' which 2.-

Figure 1 is a front elevation of a portion of 'a stoker having theinvention applied thereto:

Fig. 2 is a side sectional elevation of same: and

Fig. 3 is a plan view thereof.

In the arrangement shown, two fans 1, 2, are mounted on opposite sidesof the hopper 8, these two fans being connected by a shaft 4: alsocarrying an electric motor 5 supported on the brackets 6 so that adirect drive is secured. Connected with the shaft 4: is'a worm reductiongear 7 carrying at the bottom oftheworm wheel shaft a sprocket wheel 8.The sprocket wheel 8 is connected by a chain with a suitable speedregulating gear 9 which drives the stoker through the shaft 10 asindicated.

From each fan a connection or duct 11 is carried down the side of thehopper 3 to the opening 12 to the chamber beneath the grate 13. Apivoted air gate 1A is preferably arranged in each duct 11 so that theair supplied to each side of the grate by the fans may be. regulated.

The construction and arrangement of parts above described not only hasthe advantages set forth but also has others of great practical use inthat it enables the dust and part of the heat of the boiler room tobe'effectively removed and such room ventilated and these points will beclearly understood if the prior practice is considered.

In hand firing furnaces with induced draft the dust of the boiler roomis produced at or near the floor level, and the air being sucked intothe ash pit ventilates the room,

and also carries away the dust, or a great deal of it. The same may besaid of induced draft mechanical stokers, but these do not collect thedust to the same extent, since the dust is largely produced at thehopper where the coal is delivered either by shovel or by a chute.

With forced draft stokers, that is, stokers in which a pressure abovethe atmosphere is maintained beneath the fire, it has beencustomaryfheretofore to place the fans in such a position that they didnot collect the dust or ventilate the boiler room where such collectionand ventilation is needed, viz:

r is greater need with forced draft furnaces for such ventilation ascompared with other types of furnaces, by reason of the fact that moredust is created. There is the impossibility of entirely confining theair beneath the grate, and also it is difficult, if not impossible, toprevent some back escape of gas and dust from the furnace itself.

Again, in traveling grate stokers it is an advantage that they should bemade so that they can be removed from the furnace for repair ofbrickwork and repair of stokers: and they are, therefore, usually madeportable, or semi-portable, say by mounting on wheels. With suchconstruction as heretofore made there must be a joint between the airducts and the stokers which must be broken at the time of removal of thestokers.

This joint is liable to leak and create dust and it otherwise presentsdifficulties as regards the removal of the stoker. As in the presentinvention the fans 1, 2, are placed on the stoker itself and at a pointwhere the dust is formed, they will not only collect this dust, but theyalso, by taking away the warm air at these polnts, keep the room wellventilated. Furthermore, the fans 1, 2, being mounted, as shown, areconnected up with the stoker in such a way that the stoker, fans, andducts 11 are all removed from the furnace together without breakingjoints.

Another point is that with this arrangement the power required to drivethe fans 1, 2, is reduced, since the ducts 11 between the fans and thestoker are short and direct whereas with the old method of supplying airto the stokers the ducts were often long and tortuous, and connectionswith sharp bends were necessary in order to lead the air into thestokers. There was not only a considerable fall in air pressure betweenthe fan and stokers, requiring fans to be run at higher pressure thanwill be required according to the present invention with a consequentincrease of power, but there was also leakage in the ducts to be allowedfor requiring still more power.

What is claimed is 1. In a furnace, the combination of a mechanicalstoker, including a fuel support and a hopper, a fan or blower mountedadjacent the hopper whereby it is adapted to collect dust therefrom andwithdraw heated air from adjacent the front of the furnace, and an airduct connecting the fan casing with a chamber below the fuel supportingsurface of the stoker, all of said parts be ing bodily movable togetherfrom the furnace.

2. The combination of a mechanical stoker of the chain or endless gratetype adapted to be bodily moved into and from a furnace, a hopper forsupplying fuel to the grate, two fans supported on opposite sides ofthehopper, gearing external to the stoker for driving the fans, and airducts extending from the fan casings to a space beneath the fuelsupporting surface of the grate, the hopper, fans and ducts being bodilymovable with the Stoker.

3. The combination of a mechanical stoker of the chain or endless gratetype, a hopper for supplying fuel to the grate, two fans supported atopposite sides of the hopper, a shaft external to the grate adapted todrive both fans, air ducts permanently connecting the fan casings and aspace beneath the fuel supporting surface of the grate, and means foractuating the grate and rotating the fan driving shaft, the grate,hopper, fans and air ducts being adapted to be moved bodily as a unitarystructure relative to a furnace.

4:. The combination of a mechanical stoker of the chain or endless gratetype, a hopper for supplying fuel to the grate, two fans supported atopposite sides of the hopper, a shaft external to the grate adapted todrive both fans, air ducts permanently ing movable bodily as a unitarystructure relative to a furnace.

5. The combination of a mechanical stoker of the chain or endless gratetype, a hop per for supplying fuel to the grate, two fans supported atopposite sides of the hopper, a shaft external to the grate adapted todrive both fans, a prime mover on said shaft, means for actuating thegrate geared to said shaft, and air ducts leading from the fan casingsto a space below the fuel supporting surface of the grate, all of saidparts being movable bodily as a unitary structure relative to a furnace.

In testimony whereof I have hereunto set my hand.

WILFRED ROTHERY WOOD.

Copies of this patent may be obtained for five cents each, by addressingthe "Commissioner of Patents,

' Washington, D. G.

